public enum MessageType {
	UNKNOWN, CHECK, CHECK_RESPONSE, REGISTER, REGISTER_STATUS, 
	QUERY, QUERY_RESPONSE, REQUEST, REQUEST_RESPONSE, BYE, 
	UNICAST_UPDATE, UNICAST_UPDATE_STATUS, RESYNC, RESYNC_STATUS, 
	REMOTE_REGISTER, INVALIDATE, SEARCH, REDIRECT, EXT_SEARCH, 
	EXT_SEARCH_INVALID, SEARCH_RESPONSE, EXT_SEARCH_RESPONSE, 
	TX_END, GET_BACKUP_MSD, MSD_PROBE, MSD_PROBE_REPLY, 
	HELLO, REP_HELLO, ADD_SPACE
}